The use of polysiloxane surface active agents containing radial organic polyether groups to stabilize silicone emulsions is well known. U.S. Pat. No. 4,265,878 uses a polysiloxane surface active agent to stabilize antiperspirant stick compositions. U.S. Pat. No. 4,218,250 uses such a polysiloxane surface active agent to stabilize polish formulations. U.S. Pat. No. 4,268,499 uses these surface active agents to stabilize antiperspirant emulsion compositions. Further, U.S. Pat. No. 4,311,695 uses such surface active agents in personal care creams and the like.
Also, mention is made of U.S. Pat. No. 4,980,156, which describes improved antiperspirant compositions comprising an emulsion of an aqueous astringent in a volatile silicone fluid. Further, special mention is made of U.S. Pat. No. 4,988,506, which describes polysiloxane surface active agents having high molecular weight.
The subject polysiloxane surface active agents are generically known and are sometimes referred to as siloxaneoxyalkylene copolymers. However, their use to date has been directed to stabilizing silicone emulsions in skin care creams and antiperspirant sticks. However, their use in forming stable lotions has not been completely satisfactory, due to emulsion instability, because the variables affecting their function are not well understood. As will be shown in the appended examples, if, instead of antiperspirant sticks, lotions are made using a lipophilic organic surfactant together with a lipophilic polysiloxane copolymer (e.g., U.S. Pat. No. 4,988,504) they show low emulsion stability and relatively low freeze/thaw resistance. Surprisingly, however, it has now been found that if a hydrophilic surfactant is used together with certain lipophilic polysiloxane copolymers, in lotions, long term stable emulsions with excellent resistance to freeze/thaw cycling are obtained.
It is the object of the present invention to produce novel skin care and sunscreen lotions having superior emulsion stability containing surface active agents comprising an organic hydrophobic surfactant and a siloxane surfactant containing radial organic polyether groups.
It is another object of the present invention to provide a water-in-oil silicone emulsion having excellent freeze-thaw stability.